Preheat oven to 180°C. Grease 23cm round loose-based cake pan or spring form pan at least 7cm deep with butter; lightly sprinkle with flour.
Beat cake mix, eggs, oil, water, coffee and ground cardamom seeds in large bowl with electric mixer on low speed until moistened. Beat on medium speed 2 minutes. Pour into cake pan.
Bake 40 to 45 minutes or until toothpick inserted in center of cake comes out clean. Cool 10 minutes in pan; remove to cooling rack to cool completely.
Place chocolate in small heatproof bowl over pan of gently simmering water and let melt, stirring frequently, 5 to 10 minutes. Remove and set aside for 20 minutes.
Beat whipping cream mix and cold milk in medium bowl as directed on package. Beat in cooled chocolate until peaks form again.
Cut cake in half horizontally. Place one half of the cake on serving plate cut side up. Spread chocolate cream over top. Place remaining half of cake, cut side down on top of chocolate cream. Finish with a sprinkling of powdered sugar.
Serve alongside fruit of your choice.
Decorate with shards of chocolate for a more special presentation.